Santorini erupted massively about 3600 years ago, shattering the island of Thera. The effects of that explosion is still readily apparent today (see above). Geologic evidence shows that a tsunami similar to the Japanese tsunami of 2011 raked across the Eastern Mediterranean. The tsunami would have flowed up the Nile for miles.
I will strike the water of the Nile, and it will be changed into blood ~ Exodus 7:17The first plague is a well know phenomena called "red tide," caused by a poison producing algae brought up the Nile by the tsunami. It would suffocate fish and a lack of oxygen would force frogs onto the land (plague #2). Plus all the dead fish will cause the gnat (plague #3) and biting fly (plague #4) populations to explode. Plagues 5 and 6, disease among livestock and boils among Egyptians, would naturally follow a plague of biting flies.
Fine dust from the eruption could cause a destructive hailstorm (plague #7) by the same principle behind cloud seeding. The plague of darkness (number 9) would have certainly occurred as the ash cloud covered the sky and blotted out the sun.
We are left with only two remaining plagues. Volcanoes do not cause locust. But locust swarms are common in the Sahara Desert and the same ash caused rains that bombarded Egyptian crops with hail could have triggered a locust metamorphosis.
One theory is that, with all the rain and locust, the Egyptians stored their wet grain indoors where a deadly mold grew on it. The Egyptians use of yeast then cultured the mold. While the firstborn ate the freshest, contaminated, bread the other children would eat older bread without the mold. Because the Israelites baked their bread without yeast the mold didn't grown to deadly concentrations.